
let p = new Promise((resolve,reject)=>{
  resolve('first');
})
p.then(res=>{
  console.log(res);
  // return Promise.resolve('second');
  return new Promise(()=>{});//中断Promsie链式调用 返回一个 pendding状态的Promise对象
}).then(res=>{
  console.log(res);
  return Promise.resolve('third');
}).then(res=>{
  console.log(res);
}).catch(error=>{
  console.log(error);
})